1. Field of the Invention
The invention relates to color correction in digital processing of digital image data generated from a document image and in particular relates to modifications of colors in digital image data responsive to a user's preferences indicating problematic colors such as for a color-blind user (or other identified colors) and alternate presentations to replace the identified colors for various types of segments of the digital image data.
2. Discussion of Related Art
Color printing, copying, and scanning of an original document image has grown to a critical need in many business and personal applications. However, many viewers or users of such color documents have problems discriminating between certain colors, especially certain colors in the context of other color backgrounds. For example, a common form of color-blindness makes distinguishing red from green colors difficult. Other forms of color-blindness make distinctions between blue and yellow difficult to discern. Even outside the context of a color-blind user, some color combinations present difficulties for a variety of users to distinguish.
Computing applications adapted to generate an initial original color document may allow for a variety of color modifications or alterations to improve readability of the document when the original document is created. For example, it is common for a print dialog box in a Windows computing environment to allow a user to adopt certain color adaptations when the original document is created. However, when generating a digital image copy of such a color document image after initial creation of the document image, a particular user or recipient of the digital image may require particular color alterations or corrections according to their personal preferences to distinguish a variety of problematic colors. Thus the original document can be created with certain color alterations but a later digital image copy of the altered document image may not provide suitable correction for a particular user. As used herein, a “digital image copy” or “digital image data” of a document image refers to a digital or digitized version of the document image such as is produced by operation of a color scanner or other image digitizing devices and systems. Such a digital image copy may be applied to a printer to generate a physical or paper copy of the document image such as may be produced on a color copy machine (e.g., a device that scans the color document image and reprints a copy of the document image from the scanned digital image). Further, a digital image copy may be stored for subsequent utilization or may be transmitted to a remote device for utilization (e.g., by network transmission and/or facsimile transmission). Still further, the digital image data may be presented to a user of a viewer application program coupled to a display unit for further utilization by the user.
Although many computing applications used for generating an original color document may allow for a variety of color modifications or alterations, in producing the original document image present solutions for color correction or modification of a digital image copy of an already generated document image present a number of problems. For example, some current color correction techniques for correcting a digital image data remap all pixels of the document image to shift the color gamut or contrast. Such non-selective, overall modifications to a digital image copy of a document image may improperly alter colors in elements of the document image to an extent that the document image is unusable. For example, overall remapping of all colors in a document image may seriously degrade color photographs in the digital image copy of the document image or may improperly shift colors in a graphic object (e.g., a corporate logo) so as to incorrectly represent the intended information. Further, present solutions fail to adequately notify a user of the digital image copy of the document image that the colors have been so modified. Devoid of such notification, a user may be misled by reading information directing attention to certain objects referenced by color. For example, if a document describes an associated graphical object in the document with reference to “red lines” on the document image copy but the red lines have been “corrected” to blue, the user may not know that the correction was applied and may be confused by the document content.
It is evident from the above discussion that a need exists for improved systems and methods for flexible, selective, color correction in a digital image copy of a document image.